用于在现有 DOM 元素上动态设置属性的 Angular 指令 [英] Angular directive to dynamically set attribute(s) on existing DOM elements

问题描述

我对 Angular 有点陌生，因此当然欢迎对替代方法的反馈.

I'm somewhat new to Angular, so feedback on alternative approaches is certainly welcome.

我创建了一个名为serverMaxLengths"的指令.当指令放置在 ng-form 上时，它将从 REST API 获取数据库字段长度，然后遍历表单控制器中包含的所有输入元素的内容，并相应地设置maxlength"属性.指令如下:

I have created a directive called "serverMaxLengths". When the directive is placed on an ng-form, it will fetch database fields lengths from a REST API and then will walk the contents of all input elements contained within the form controller, and will set the "maxlength" attribute accordingly. The directive is as follows:

myApp.directive('serverMaxLengths', function ($log,$http,$compile) {
return {
    restrict: 'A',
    require: '^form',
    link: function (scope, elem, attrs, formController) {
        if (!formController) return;


        var httpConfig = {
            method: 'GET',
            url: myAppRestURL + "/validator-rest?action=getDBFieldLengths"
        };

        $http(httpConfig)
            .success(function (data, status, headers, config) {

                if (typeof data.isValid != 'undefined') {
                    if(data.isValid){
                        var inputElem = elem.find('input');
                        angular.forEach(inputElem, function (value, key) {
                            var thisElement = angular.element(value);
                            if (typeof thisElement[0] !== 'undefined') {
                                if(typeof data.dbFieldLengths[thisElement[0].id] !== 'undefined'){
                                    if(data.dbFieldLengths[thisElement[0].id] > 0){
                                        thisElement.prop("maxlength", data.dbFieldLengths[thisElement[0].id]);
                                        thisElement.prop("ng-maxlength", data.dbFieldLengths[thisElement[0].id]);
                                        thisElement.prop("ng-minlength", 0);
                                        $compile(thisElement)(scope);
                                    }
                                }
                            }
                        });
                    }else{
                        ...
                    }
                }else{
                    ...
                }


            }).error(function (data, status, headers, config) {
                ...
            });

    }
};});

这有效.据我所知， $compile 在指令执行时替换现有元素.

This works. Insofar as I understand, $compile is replacing the existing element(s) when the directive is executed.

我想知道实现这一目标的更好的Angular"方式是什么?我想要一个非常简单的解决方案，不需要将指令放置在任何实际输入元素上(我希望一切都一次性发生).

I'm wondering what a better "Angular" way of achieving this might be? I wanted a very simple solution that doesn't require the directive to be placed on any of the actual input elements(I want everything to happen in one go).

最后，获取最大长度集的字段之一具有分配给它的 UI Bootstrap Typeahead 指令.在应用maxlength"之前，该指令按预期工作.但是，通过上述方法在字段上设置maxlength"的应用后，当输入失去焦点(否则它起作用)时，提前输入会呈现TypeError:无法读取未定义的属性'长度'"错误.这让我担心这种方法以及幕后发生的事情.

*注意:通过执行以下操作来解决提前类型错误:

*Note: The type ahead error is resolved by doing:

$compile(thisElement.contents())(scope);

代替:

$compile(thisElement)(scope);

感谢您的任何反馈/建议/想法.

Thanks for any feedback/suggestions/thoughts.

推荐答案

$compile(thisElement.contents())(scope);解决了首要关注的问题.

The addition of $compile(thisElement.contents())(scope); resolved the issue that was of primary concern.

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